Few medical doctors who treat depression dispense detailed dietary advice, but some experts believe that's a mistake. The way you eat affects the way you feel, according to Dr. Richard Brown and Teodoro Bottiglieri, Ph.D., co-authors of the book Stop Depression Now (Berkley Publishing Group, 2000). The book is about SAMe (pronounced "Sammy"), an over-the-counter nutritional supplement you can buy in supermarkets, vitamin shops, and health-food stores.

Here are a few critical tips that they say may help you beat the blues, whether or not you take supplements of SAMe:

Get plenty of B vitamins. The B vitamins folate (also known as folic acid) and B12 appear to play a role in preventing depression. You've probably heard of homocysteine, an amino acid that can accumulate in your system and damage arteries, leading to heart disease and strokes. High levels of homocysteine also appear to be associated with poor mental health, says Dr. Bottiglieri. Your body needs a healthy supply of B vitamins to convert homocysteine into SAMe, which in turn makes your body produce and use brain chemicals that fight depression.

Studies show that about one-third of depressed people have low levels of folate. You may already be getting sufficient folate and B12 each day if you eat five servings of fruit and vegetables -- especially orange juice, leafy greens, beans, and bananas. Breakfast cereals and bread (especially whole-grain) are good sources, too. Multivitamins provide more than the recommended daily intake of folate and B12, though Dr. Bottiglieri says that may still be too low for some people, adding that older people especially should consider taking a supplement, since they may have trouble absorbing certain vitamins.

Eat fish a few times a week. Fatty cold-water varieties, such as salmon, albacore tuna, sardines, and mackerel, are rich in omega-3 fatty acids. Not only do omega-3's promote heart health, but they are metabolized by the body to produce another compound, known simply as DHA, which is vital to the formation of brain tissue.

Beware of convenience foods. Junk foods and processed meats are filled with saturated fats and compounds that cause the creation of free radicals, which can destroy brain cells.

The good news: The foundation for a depression-fighting diet also happens to be the basis of a balanced nutrition plan that will also help to combat other conditions, such as heart disease and cancer.